How to Deal with Blossom End Rot

Blossom end rot is a common problem with both green and ripe tomatoes. However, it is not limited to tomatoes. Squash, eggplant, peppers, and virtually all fruiting plants can be affected.
Because blossom end rot of tomatoes is so common and devastating to a tomato crop it can be very discouraging for a gardener to put in so much time and effort to produce a good crop only to see it ruined by the condition.

What it looks like

Tomato Blossom End Rot

Tomato blossom end rot appears as a black or gray sunken spot at the bottom end of the tomato. It begins as a 1/2 inch spot and slowly spreads. While the condition itself is limited, the affected tomato is subject to secondary infections and diseases which can cause the entire fruit to rot. When growing tomatoes you will see it most often during the rapid growth phase, usually during hot, dry weather, but it can be seen at any time.

Causes of Blossom End Rot

Blossom end rot is caused by a calcium deficiency that is a result of wide fluctuations in available water. It is especially prevalent when  rapidly growing fruit are subject to a period of drought. Since it is a physiological condition it does not spread from fruit to fruit or to other plants. Neither does it respond to disease treatments such as fungicides or insecticides. High levels of nitrogen make the condition worse. Damaging the sensitive roots by planting in cold soil or cultivating too close to the plants will result in reducing the plant’s ability to absorb moisture.

Cure

Make sure soil has sufficient Ca++ with soil testing if necessary.
Use low nitrogen fertilizer that is high in superphosphate such as 4-12-4 or 5-20-5.
Water evenly and deeply.
If cultivation is necessary don’t get too close to the plants or cultivate too deeply to prevent damage to the roots. A strong root system is vital to providing the plants with adequate water and nutrients.
Apply organic mulch after the plants are well established to preserve soil moisture.

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